1. Field of the Invention
The present invention relates to an elastomer composition and a rubber roller formed by using the elastomer composition. More particularly, the present invention relates to an elastomer composition which is extremely excellent in wear resistance while having a suitable hardness and which is suitably used as a rubber roller used in a paper feeding mechanism of OA equipment such as an inkjet printer, a laser printer, an electrostatic copying apparatus or a facsimile apparatus, or an automatic deposit payment machine (ATM), or the like, as well as to a method of producing the same.
2. Description of the Background Art
A paper feeding rubber roller made of a rubber composition, an elastomer composition, or the like is used in a paper feeding mechanism for conveying paper, film, or the like in OA equipment such as an inkjet printer, a laser printer, an electrostatic copying apparatus or a facsimile apparatus, in an automatic deposit payment machine (ATM), or the like.
In recent years, OA equipment for personal use is particularly increasing in number, and multiple kinds of paper are passed therethrough. In order to obtain stable conveying property for paper, film, or the like for multiple kinds of paper, there is a demand for ensuring a high wear resistance and a high friction coefficient. Thus, various proposals are made on elastomer compositions, rubber compositions, and the like suitable for use as a rubber roller such as described above.
For example, in order to obtain a large friction coefficient to paper and an excellent wear resistance when used in a paper feeding rubber roller, the applicant of the present invention proposed in Japanese Laid-open Patent Publication 11-228708 a rubber composition containing 100 to 300 parts by weight of hydrogenated styrene thermoplastic elastomer with respect to 100 parts by weight of rubber where the rubber is dynamically crosslinked by a resin crosslinking agent and dispersed in the hydrogenated styrene thermoplastic elastomer.
The rubber composition proposed in the above-mentioned patent document is excellent in wear resistance with low hardness and can keep exhibiting a good paper feeding performance for a long period of time. In recent years, however, inkjet printers, laser beam printers, copying apparatus, and the like such as described above tend to have a reduced number of components for the purpose of cost reduction, so that the load imposed on the rubber roller is increasing thereby demanding those that can exhibit a higher performance.
In particular, in order to simplify the paper feeding mechanism, a mechanism is proposed having a construction such that the rubber roller rotates by idling relative to a releasing member each time a sheet of paper is fed. For this reason, not only the friction coefficient but also the wear resistance must be enhanced. In particular, against the friction generated when the rubber roller is slipped by receiving load such as in idling rotation, a high mechanical strength is required, and a high tensile strength TB is required.
In conventional paper feeding rubber rollers, it was sufficient to have a wear resistance of a degree such as required against the friction generated by slight slippage on paper when the paper was fed. Also, since the load imposed on the rubber roller was low, mechanical strength such as tensile strength was not so important. Regarding vulcanized rubber, it is possible to prepare a blend having a tensile strength TB high to some extent and a high friction coefficient. However, methods of producing vulcanized rubber will be costly. Therefore, it is desired to prepare a rubber roller in a step of resin with the use of a thermoplastic elastomer composition in view of good productivity and excellent physical property.
Further, even Example 1 and Example 1a providing the highest performance in the above-mentioned patent document can provide a tensile strength TB of 4.0 MPa. With this tensile strength, a large amount of rubber powder is created to reduce the weight greatly by wear when the rubber roller is rotated by idling and worn.
The present invention has been made in order to solve the aforementioned problems of the prior art, and an object of the present invention is to provide an elastomer composition being extremely excellent in wear resistance while having a suitable hardness as well as a method of producing the elastomer composition. Another object of the present invention is to provide a rubber roller that realizes a low hardness and a good wear resistance and is excellent in wear resistance particularly at the time of idling rotation.